What Causes Nausea And Lightheadedness?

I have been having a bunch of weird symptoms. Right now I am nauseous if I stand up (so I am laying down flat to keep that from happening), that comes and goes every day. I have had a stiff neck for a month now. My blood sugar is on a rollar coaster. My temperature is a lot lower than usual (normally I am a 98,9 person but I have been in the 97 - 98.1 range lately). And I have been getting weird waves of light headedness. What do I do?